Isomerism Flashcards

1
Q

Another word forEZ isomerism

And what is needed for it to occur?

A

Geometric isomerism

A carbon - carbon double bond to prevent rotation, and 2 different groups attached to the carbon atom

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2
Q

What is optical isomerism

A

When isomers have the same molecular and structural formula, but have a different affect in the plane of polarised light

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3
Q

What are enantiomers

A

Non super impossible mirror images

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4
Q

Why can’t a carbon atom that’s part of a double bond or a carbonyl (C=O) atom not be chiral?

A

Due to the mirror image relationship and the fact isomers can’t be superimposed on eachother, it can’t be chiral as the carbons only have 3 Different atoms or groups attached

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5
Q

How does optical isomerism arise?

A

It arises from molecules which have 4 different atoms or groups of atoms attached to the tetrahedral carbon (chiral)

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6
Q

Describe an optically active compound (enantiomer)

A

It has the ability to rotate the plane of polarised light left or right, amount of rotation is measured by a polarimeter

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7
Q

What is an equivocal mixture of 2 different enantiomers called?

A

Race mate

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8
Q

Why is a race mate (equinmolar mixture of 2 enantiomers) optically INACTIVE?

A

Because the rotating effect of one enantiomer cancels out the effect of another

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9
Q

What is the separation of a race mate into component enantiomers called?

A

Resolution

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10
Q

What is a stereoisomer?

A

Have same molecular and structural formula but atoms arranged differently in space

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11
Q

How can you distinguish between enantiomers?

A

Rotate the plane of polarised light in opposite directions

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12
Q

What is the amount of rotation measured using?

A

A polarimeter

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13
Q

Ratio of an equinmolar mixture of 2 enantiomers (racemate)

A

1:1

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14
Q

An equinmolar mixture of 2 enantiomers is optically inactive- why?

A

The rotating effect of one enantiomer cancels out the effect of another

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15
Q

Define an enantiomer and its ability

A

Non superimposable mirror images

Has the ability to rotate the plane of polarised light left or right

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16
Q

Is an enantiomer optically active or inactive?why?

A

Active !

Because it has the ability to rotate the plane of polarised light left or right

17
Q

Give some examples of Carbons / compounds that aren’t Chiral

Why?

A

C=O
C=C
Benzene

Due to the mirror image relationship and the fact isomers cannot be superimposed on eachother - must have 4 different atoms attached to the tetrahdral (chiral) Carbon!

18
Q

What is meant by a compound that shows optical activity

A

Has ability to rotate the plane of polarised light in opposite directions

19
Q

Why is something optically inactive

A

Rousting effect of one enantiomer cancels out affect of another

20
Q

What is meant by the term enantiomer

A

An optically active isomer that had the ability to rotate the plane of polarised light in opposite directions